Detonating or blasting cap



J. B. SMITH DETONATING 0R BLASTING CAP Filed Feb. lO. 1923 Patented July29, 1924.

s STATE` 1,502,154 Parar OFFICE.

JOHN B. SMITH, F EAST .AI/EON, ILLINIS, ASSIGNOR T0 WESTERN CARTRIDGECOM- PANY, 0F EAST ALTON, ILLINOIS, A CORPORATION 0F DELAWARE.

DETONATING 0R BLASTING CAP.

Application led February 10, 1923. Serial No. 618,243.

To all whom t may concem.'

Be it known that I, JOHN B. SMITH, a citizen of the United States, andresiding at East Alton, county of Madison, Illinois, have invented thenew and useful Improvement in Detonating or Blasting Caps, of which thefollowing is a specication.

This invention relates to explosives, and more particularly todetonating or blasting 1o caps. f

This ap lcation is a continuation of application erial Number 485,047,tiled July 15, 1921, as to common subject matter.

A detonating or blasting cap usually consists of a drawn shellhaving acharge of an explosive compound, such as mercuiic ulmirrate or a mixtureof mercurio fulminate and potassium chlorate.

Of the aromatic nitro-compounds, trinitro-toluene is the most stable. Itis less dense and slower in detonation than'picric acid but has thegreat advantage of being more stable, does not form the sensitive saltsand is less poisonous. Moreover, it is fairly cheap and can betransported with safety. Its use as a priming charge for blastmgpurposes is, however, limited on account of its being more insensitiveto detonation than other compounds of the nitrohydrocarbon group. Thusit requires more than twice the amount of fulminate of mercury to effectdetonation than does picric acid, and even double the amount of theinitiator ofdetonation will not always secure its detonation.Furthermore at the commencement of the detonation there are oftenirregularities andthe velocity may not be maintained.

Picric acid will detonate violently when L0 submitted to a moderateblow, one gram of fulminate of mercury being sufticient to detonate thesame. Picric acid further has the advantage that it will induce thedetonation to neighboring parts of a less sensitive L5 explosive.Moreover when mixed with trinitro-toluene, it has the effect ofrendering the latter more sensitive to detonation.

The character and velocity of a wave of detonation is of the same orderas that of 30 sound waves through solids. Accordingly when an initiatorof detonation sets up an initiating wave so as to detonate a lesssensitive explosive, the waves combine to produce beats in a resultantwave whose amplitudev may reach high limits. Accordingly such aresultant wave will readily detonate a comparatively insensitiveexplosive.

One of the objects of this invention, therefore, is to combine thecharacteristics of a comparatively sensitive explosive, such as picricacid, with a less sensitive but more stable explosive, suchastrinitro-toluene, in order to produce a combined charge having thedesired characteristics and requiring a minimum amount of the initiatorof detonation, such as fulminate of mercury.

Another object of this invention is to devel'op a detonating or blastingcap, whereby a cheap and otherwise desirable, but comparativelyinsensitive, explosive may be employed as the major part of the charge.

Further objects will appear from the detail description taken inconnection with the' accompanying drawing, in which: i Figures 1 and 2are longitudinal sections through a detonating or blasting cap embodyingthis invention and showing its method of formation. f

In accordance vwith an embodiment of this invention, the shell 1contains a combined charge 2 comprising a mixture of a comparativelysensitive explosive, such as picrid acid, mixed with a less sensitiveexplosive, such a's trinitro-toluene, together with an initiator ofdetonation 3, such as fulminate 85 of mercury. The components of thecharge are uniformly mixed and forced or pressed into the shell underhigh pressure and preferably the charge is recessed as shown at 4, thisrecess being preferably conical. The initiator 3 is then placed over thecharge so as to Ell the Arecess and a flanged disc'5 having a centralperforation 6 may be placed over the initiator and pressed intoposition. The disc may then be capped with a waterproofing film 7 of amaterial which is pervious to fire, such as a mixture of nitrated cottonin ethyl-acetate. It is to be understood that the loaded cap may be usedwith any suitable fuse orother igniter. The ordinary trinitro-toluene ofcommerce, which is the 1-2-4-6 or alpha isomer having a melting point of80.6 C. and of a fineness to pass through an 80 mesh screen may be used.However, the 1--2-3-4 or beta isomer having a melting point of 112 C. orthe 1-3 -4-6 or-gamma isomer having a melting point of 104 C. may beused.

Upon ignition of the initiator and the detonation of the same', it willset up a wave 110 of detonation which will detonate the more sensitivecomponent of the mixture, such as picric acid, so as to set up asupplementary wave of detonation. The two waves will combine so as toproduce a resultant wave of detonation having beats whose amplitude ishigher than that of either the initiating or supplementary wave. Thecombined wave will, therefore, serve to detonate the less sensitivecomponent (trinitro-toluene) of the chargei mixture. Furthermore, due tothe fact that the charge is recessed, the effect is intensifiedconsiderably for the reason that when the waves of detonation reach theqcone-shaped cavity, waves of compression start out perpendicular to theconical surface and IJthese meet in the center producing a much greatereil'ect than is the caseif the charge is not recessed. Furthermore inview of the fact that the more sensitive component of the charge isdistributed throughout the less sensitive-component, the detonation ofthe less sensitive component is not only accomplished by pressure butthe temperature is suddenly raised throughout the mass by the detonationof the less sensitive component, thereby enhancing the detonation of thelatter. This distribution of the more sensitive component, such aspicric acid, throughout the mass of the less sensi'- tive componentfurthermore has the effect of inducing the detonation of the former toneighboring particles of the latter and also to render it more sensitiveto detonation.

The result is, therefore, that by the employment of the compounds of thecharacter of and arranged as described, the amount of the fulminate maybe considerably reduced, due to the fact that the amount required isonly that necessary to detonate the more sensitive component, such aspicric acid. Moreover the amount of the charge itself required todetonate a given blasting charge may also be considerably reduced, dueto the fact that the explosive wave set up by the less sensitivel chargecomponent combines with the initiating and supplementary waves and theirresultant wave, to form a inal resultant wave of detonation formingbeats and having also a high amplitude. Thus as a practical3 example, ithas been found that a blasting cap described as above containing a totalcharge including the initiator of twelve (l2) grains, will .have a powerequivalent to that of a blasting cap containing a charge of sixteen (16)grains composed of eight-five per cent (85%) of fulminate of mercury andfifteen per cent (15%) of chlorate of potassium. Accordingly the volumeof the cap is not only reduced, but its cest is considerably cheapened'.

The following is a typical example of the proportions found to securethe best results when using a mixture of trinitro-toluene and picricacid as a combined charge and fulminate .of mercury as an initiator` ofdetonation.

Trinitro-toluene 36.4 Picric acid 19.6% F ulminate of mercury 44.0%

The amount of each of the ingredients may, however, be varied to suitrequirements in any particular case.4 )Vhile it has been found that amixture of'trinitro-toluene and picric acid is the most suitable foraccomplishing the objects of this invention, it will be understood lthatthe character of the charge components may be varied. Thus otheraromatic nitro-compounds which are more sensitive to detonation may beused instead of picric acid as, for instance, trinitroxylol,trinitronapthalene, trinitroresorcinate, tetranitroresorcinate,trinitromethylaniline, tetranitromethylaniline, hexanitro diphenylamine,trinitrocresol, etc.

Furthermore two or more of such sensitive components may be used incombination with a less sensitive component. Furthermore initiators ofdetonation other than fulminate of mercury may be used, such as leadazide.

While reference has been had to certain theories in order to explain theadvantageous features of this invention, it is and will be understoodthat this invention is not limited to any theory of operation. It isfurther obvious that various changes may be made' in detail withoutdeparting from the spirit of this invention; it is, therefore, to beunderstood that this invention is not to be limited to the specificdetails shown and described.

Having' thus described the invention, what is claimed is: e

1. A detonating or blasting cap containing as a combined charge asensitive explosive mixed with a less sensitive aromatic nitro-compound.

2. A detonating or blasting cap containing as a combined charge asensitive aromatic nitro-compound mixed with a less sensitive aromaticnitro-compound.

3. A detonating or blasting cap containing as a combined charge asensitive explosive mixed with trinitro-toluene.

4. A detonating lor blasting cap containing as a combined charge asensitive aromatic nitro-compound mixed with trinitrotoluene.

5. A detonating or b'lasting cap containing as a charge picric acidmixed with trinitro-toluene.

6. A detonating or blasting` cap containing as a charge a small quantityof sensitive explosive mixed with a larger quantity of a less sensitivearomatic nitro-compound.-

7. A detonating or blasting cap containing as a charge 19.6 parts ofpicric acid mixed with 36.4 parts of trinitro-toluene.

8. A detonating or blasting cap comprising, a shell containing as acombined charge a sensitive explosive mixed with a less sensitivearomatic nitro-compound, together with an initiator of detonationtherefor.

9. A detonating or blasting cap comprising, a shell containing as acombined charge 19.6 parts of picric acid mixed With 36.4 parts oftrinitro-toluene, together With 44 parts of fulminate of mercury.

10. A detonating or blasting cap comprising, a shell containing as arecessed charge, a sensitive explosive mixed with a less sensitivearomatic nitro-compound together with an initiator of detonation in therecess.

11. A detonating or blasting cap comprising, a shell containing as arecessed charge, picric acid mixed kWith trinitro-toluene togather withfulminate of mercury in the recess.

12. In the art of making detonating or blasting caps, the processcomprising, mixing a sensitive explosive With a less sensitive aromaticnitro-compound and placing an initiator of detonation `on the charge.

13. In the art of making detonating or blasting caps, the processcomprising, mixing a sensitive explosive With a less sensitive aromaticnitro-compound, compressing the charge in the shell and placing aninitiator of detonation on the charge.

14. In the art of making detonating or blasting caps, the processcomprising, mixing picric acid with trinitro-toluene and placingfulminate of mercury on the charge.

, the charge in the shell to form a recess 1n the charge, and placing aninitiator of detonation on the charge.

16. A detonating or blastlng cap compri.-

ing, a main charge, a supplementary charge of greater sensitivenessmixed therewith, and an initiator of detonation of greater sensitivcnessthan the supplementary charge.

17. A detonatiiig or blasting cap comprising a shell containing, acharge of trinitrotoluene and picric acid, and a priming therefor.

18. A detonating or blasting cap, containing as a charge, an intimatemixture of trinitrotoluene and pieric acid,.and an agent to initiatedetonation.

19. A detonating or blasting cap, containing as a charge, a mixture oftrinitrotoluene, picric acid and a nitrated aromatic compound, capableotl being detonated by a more sensitive. substance.

20. A detonating or blasting cap, containing as a charge, a mixture oftrinitrotoluene, picric acid and a nitrated aromatic compound, and asensitizing agent.

21. A detonating or blasting cap, containing, fulminate of mercury andan intimate mixture of trinitrotoluene and picric acid.

In testimony whereof I aiiix my signature this 29thv day of January,1923.

JOI-IN B. SMITH.

